This movie addresses profound medical, moral, philosophical and cosmological issues. Unfortunately it fails to adequately explore any of them with competence. Segel was miscast. He was utterly unconvincing as a neurologist. He seemed clumsy rather than educated. It turns out this is a romance and commentary of grief disguised as a sci-fi film. I never saw the validity of the romance. Unsatisfying as a sci-fi. Unsatisfying as a romance. It's one saving virtue is that it was thought provoking. The audience was challenged to answer questions left unanswered by the film.